Schottky barriers to semiconducting polymers

This paper reports the results of a systematic investigation of the dc and ac admittance of the Schottky barrier formed at the interface between aluminium and poly(3-methyl thiophene) prepared by electropolymerisation. The work shows that interfacial layers are readily formed in polymer Schottky barriers and that the effect of the layer may be controlled by the processing methods used. The presence of the interfacial layer has enabled us, for the first time, to obtain evidence, albeit circumstantial, for the presence of inversion and therefore of minority carriers in semiconducting polymers. Since the interfacial layer plays a significant role in controlling device behaviour its presence must be taken into account when analysing experimental results.<>